Yes, by using the Rietveld refinement on an XRD pattern and knowing the crystal structures of all the phases present in your sample you can easily find the weight percentages
you can choose any user friendly softwares such as POWDER CELL , GSAS, MATCH, etc., which will give the quantify ratio either in manual or automatic mode. you just compare the stimulated pattern with the observed pattern then u can proceed accordlngly...